net/virtio: fix queue setup consistency

net/virtio: fix queue setup consistency

In rx/tx queue setup functions, some code is executed only if
use_simple_rxtx == 1. The value of this variable can change depending on
the offload flags or sse support. If Rx queue setup is called before Tx
queue setup, it can result in an invalid configuration:

- dev_configure is called: use_simple_rxtx is initialized to 0
- rx queue setup is called: queues are initialized without simple path
  support
- tx queue setup is called: use_simple_rxtx switch to 1, and simple
  Rx/Tx handlers are selected

Fix this by postponing a part of Rx/Tx queue initialization in
dev_start(), as it was the case in the initial implementation.

Fixes: 48cec290a3d2 ("net/virtio: move queue configure code to proper place")
Cc: stable@dpdk.org
Signed-off-by: Olivier Matz <olivier.matz@6wind.com>
Acked-by: Yuanhan Liu <yliu@fridaylinux.org>